package network;
//
//import java.io.IOException;
//import java.net.DatagramPacket;
//import java.net.DatagramSocket;
//import java.net.SocketException;
//import java.nio.charset.StandardCharsets;
//
//public class UdpEchoServer {
//    private DatagramSocket socket = null;
//
//    public UdpEchoServer(int port) throws SocketException {
//        socket = new DatagramSocket(port);
//    }
//
//    public void start() throws IOException {
//        System.out.println("服务器启动!");
//        while(true) {
//            //每次循环,就是一个请求响应的过程
//            //1.读取请求并解析
//            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
//            socket.receive(requestPacket);
//            //基于字节数组构造String
//            String request = new String(requestPacket.getData(),0,requestPacket.getLength());
//            //2.根据请求计算响应
//            String response = process(request);
//            //把响应返回客户端
//            //构造一个DatagramPacke作为响应对象
//            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(StandardCharsets.UTF_8),
//                    response.getBytes().length,requestPacket.getSocketAddress());
//            socket.send(responsePacket);
//
//            //打印日志
//            System.out.printf("[%s:%d] req: %s, resp: %s\n", requestPacket.getAddress().toString(),
//                    responsePacket.getPort(),request,response);
//
//        }
//    }
//
//    private String process(String request) {
//        return request;
//    }
//
//    public static void main(String[] args) throws IOException {
//        UdpEchoServer server = new UdpEchoServer(9090);
//        server.start();
//    }
//}


import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.nio.charset.StandardCharsets;


public class UdpEchoServer {
    private DatagramSocket socket = null;
    public UdpEchoServer(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }

    public void start() throws IOException {
        System.out.println("服务器启动!");
        while(true) {
            //1.读取请求并解析
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            //基于字节数组构造String
            String request = new String(requestPacket.getData(),0,requestPacket.getLength());
            //2.基于请求计算响应
            String response = process(request);
            //把响应返回给客户端
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(StandardCharsets.UTF_8),0,
                    response.getBytes().length,requestPacket.getSocketAddress());
            socket.send(responsePacket);

            //打印日志
            System.out.printf("[%s:%d] req: %s, resp: %s\n",responsePacket.getAddress().toString(),requestPacket.getPort(),
                    request,response);
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoServer server = new UdpEchoServer(9090);
        server.start();
    }
}